This is a 5-year renewal application to support 5 postdoctoral trainees for a broad training program in Academic Endocrinology. This program has been in place at the Brigham and Women's Hospital/Harvard Medical School since 1985 and has been highly successful in training physician-scientists and basic scientists, many of whom remain in academic endocrinology. In the last 10 year period, more than 70% of the 14 trainees who have completed their training remain in a research career. The faculty combines both the physician- scientists of the Endocrinology Division with those basic scientists of the Harvard Medical School faculty whose research is significantly related to endocrinology and who have a past and current history of collaborative interactions with Program faculty members in the Endocrinology Division. Over the last ten years, these 21 faculty members have trained over 250 postdoctoral fellows, the great majority of whom remain in research- related careers, either in academic positions or in industry. The faculty are well-funded, with estimated modified direct costs per annum of over $50 million. The 5 trainees appointed each year will be individuals with MD, PhD, or MD/PhD degrees and they will undertake 3-4 years of an intensive research experience with an emphasis on translational investigation. The goal of the program is to provide the trainees with sufficient expertise to apply successfully for mentored research awards, such as K23, K08, K01 or K99 awards, or independent research grants such as R01 grants, as indicated, to ultimately develop into translational endocrine investigators who will address the great needs for research into endocrine and metabolic disorders that are so prevalent and cause such great morbidity in our society. The areas of research interest of the faculty include regulation of energy expenditure, insulin sensitivity, the role of the iodothyronin deiodinases in controlling differentiation and cell division via local activation and inactivation f thyroid hormone, mechanisms of calcium signaling, the process of bone development and its clinical implications, neuroendocrinology, the study of G protein-coupled receptors, the control of skeletal muscle development, differentiation, and repair, and mechanisms of muscle proteolysis in cachexia and muscle atrophy, the mechanisms of steroid hormone action, and the epidemiology of diabetes, obesity, and vitamin D deficiency disorders. There is also a strong emphasis on genetics, epigenetics, and new technologies for translating science into therapeutics. Individuals in this program will be trained to translate the insights they gain to develop strategies for the treatment and prevention of common endocrinology-based public health problems, including diabetes, obesity and osteoporosis.